The effects of nicotine on activation of extracellular regulated kinase (Erk)1/2 and p38 mitogen-activated protein kinase (MAPK) induced by 1-methyl-4-phenylpyridinium ion (MPP
) in astrocytes. MPP+ increased Erk1/2 and p38 MAPK phosphorylation indicative of their activation. (A,B) Astrocytes were treated with MPP+ 200 μmol/l for various lengths of time as indicated.(C,D) Astrocytes were pretreated with nicotine 10 μmol/l in the absence or presence of MLA 100 nmol/l for 30 minutes and then challenged with MPP+ 200 μmol/l for 30 minutes. After treatment, astrocytes were harvested, and levels of phosphorylated (A,C) Erk1/2 and (B,D) p38 MAPKs were analyzed. Upper panel shows densitometric analysis of the phosphorylated forms of Erk1/2 and p38 MAPK, while the lower panel shows representative blots. Data are presented as the mean ± SEM of four independent experiments. *P < 0.05 and **P < 0.01 versus the control group; #
P < 0.05 and ##
P < 0.01 versus the MPP+ treatment alone group.